Attachment 8 - FEDERAL METEOROLOGICAL HANDBOOK No. 1-2019.pdf

OFFICE OF THE FEDERAL COORDINATOR FOR

METEOROLOGICAL SERVICES AND SUPPORTING RESEARCH

U.S. DEPARTMENT OF COMMERCE/ National Oceanic and Atmospheric Administration

FEDERAL METEOROLOGICAL HANDBOOK No. 1

Surface Weather Observations and Reports

FCM-H1-2019

Washington, D.C.

July, 2019

CHANGE AND REVIEW LOG

Use this page to record changes, notices and reviews.

Change Number Page Numbers Date Posted Initials

Changes are indicated by a vertical line in the margin next to the change.

Review Date Comments Initials

THE OFFICE OF THE

FEDERAL COORDINATOR

FOR

METEOROLOGICAL SERVICES AND

SUPPORTING RESEARCH

1325 EAST-WEST HIGHWAY, SUITE 7130

SILVER SPRING, MARYLAND 20910

301-628-0112 ofcm.mail@noaa.gov

FEDERAL METEOROLOGICAL HANDBOOK

NUMBER 1

SURFACE WEATHER OBSERVATIONS AND REPORTS

FCM-H1-2019

Washington, D.C.

July 24, 2019 iv v

Summary of Changes This change to FMH-1, published July 24, 2019, replaces the November 30, 2017 version and accomplishes the following general objectives:

• Update new speci category with the following specific changes: Chapter 2:

section 2.5.2 Aviation Selected Special Weather Report (SPECI), a. Criteria for SPECI, 6. PRECIPITATION with the following:

o d). snow begins, ends, or changes intensity.

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Table of Contents

Contents

CHANGE AND REVIEW LOG

Summary of Changes ................................................................................................... v Table of Contents ......................................................................................................... vi List of Tables ................................................................................................................ ix

CHAPTER 1: INTRODUCTION

1.1 Purpose

1.2 Applicability of Standards

1.3 Relation to Other Handbooks and Manuals

1.4 Format of This Handbook

1.5 Changes to The Handbook

1.6 Agency Procedures and Procedural Changes

1.7 Reference Library

1.8 Unforeseen Requirements

1.9 Other Questions and Suggestions Regarding FMH-1

CHAPTER 2: SURFACE WEATHER OBSERVATION PROGRAM

2.1 General

2.2 Scope

2.3 Surface Weather Observation Program

2.4 Aviation Weather Observing Locations

2.5 Types of Reports

2.6 Observing Standards Applicable to All Stations

2.7 Recency of Observed Elements

2.8 Dissemination

2.9 Report Filing Time

2.10 Delayed Reports

CHAPTER 3: CERTIFICATION AND QUALITY CONTROL

3.1 General

3.2 Scope

3.3 Certification Requirements

3.4 Quality Control

3.5 Quality Control Performed at Central Locations

3.6 Customer Feedback

CHAPTER 4: OBSERVATIONAL RECORDS

4.1 General

4.2 Scope

4.3 Types of Records

CHAPTER 5: WIND

5.1 General

5.2 Scope

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5.3 Wind Parameters

5.4 Wind Observing Standards

5.5 Wind Reporting Standards

5.6 Summary of Wind Observing and Reporting Standards

CHAPTER 6: VISIBILITY

6.1 General

6.2 Scope

6.3 Visibility Parameters

6.4 Visibility Observing Standards

6.5 Visibility Reporting Standards

6.6 Summary of Visibility Observing and Reporting Standards

CHAPTER 7: RUNWAY VISUAL RANGE

7.1 General

7.2 Scope

7.3 Runway Visual Range (RVR) Parameter

7.4 Runway Visual Range Observing Standards

7.5 Runway Visual Range Reporting Standards

7.6 Summary of Runway Visual Range Observing and Reporting Standards

CHAPTER 8: PRESENT WEATHER

8.1 General

8.2 Scope

8.3 Present Weather Parameters

8.4 Present Weather Observing Standards

8.5 Present Weather Reporting Standards

8.6 Summary of Weather

CHAPTER 9: SKY CONDITION

9.1 General

9.2 Scope

9.3 Sky Condition Parameters

9.4 Sky Condition Standards

9.5 Sky Cover Reporting Standards

9.6 Summary of Sky Condition Observing and Reporting Standards

CHAPTER 10: TEMPERATURE AND DEW POINT

10.1 General

10.2 Scope

10.3 Temperature and Dew Point Parameters

10.4 Temperature and Dew Point Observing Standards

10.5 Temperature and Dew Point Reporting Standards

10.6 Summary of Temperature and Dew Point Observing and Reporting Standards .. 2

CHAPTER 11: PRESSURE

11.1 General

11.2 Scope

11.3 Pressure Parameters

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11.4 Pressure Observing Standards

11.5 Pressure Reporting Standards

11.6 Summary of Pressure Observing and Reporting Standards

CHAPTER 12: CODING

12.1 General

12.2 Scope

12.3 METAR/SPECI Code

12.4 Format and Content of the METAR/SPECI

12.5 Coding Missing Data in METAR/SPECI

12.6 Coding the Body of the METAR/SPECI

12.7 Remarks (RMK)

APPENDIX A: GLOSSARY

APPENDIX B: LIST OF ABBREVIATIONS AND ACRONYMS

APPENDIX C: SENSOR STANDARDS

APPENDIX D: RUNWAY VISUAL RANGE TABLES

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List of Tables Page Table 5-1: Estimating Wind Speed ............................................................................... 5-2 Table 5-2: Summary of Wind Observing and Reporting Standards .............................. 5-3 Table 6-1: Reportable Visibility Values ......................................................................... 5-4 Table 6-2: Summary of Visibility Observing and Reporting Standards and Procedures ................................................................................................. 5-4 Table 7-1: Summary of RVR Observing and Reporting Standards .............................. 7-2 Table 8-1: Intensity of Rain or Ice Pellets Based on Rate-of-Fall ................................. 8-3 Table 8-2: Estimating Intensity of Rain ......................................................................... 8-3 Table 8-3: Estimating Intensity of Ice Pellets ................................................................ 8-3 Table 8-4: Intensity of Snow, Snow Pellets or Drizzle Based on Visibility .................... 8-4 Table 8-5: Notations for Reporting Present Weather ................................................... 8-6 Table 8-6: Summary of Present Weather Observing and Reporting Standards ........... 8-8 Table 9-1: Criteria for Variable Ceiling ......................................................................... 9-3 Table 9-2: Reportable Contractions for Sky Cover ....................................................... 9-4 Table 9-3: Priority for Reporting Layers........................................................................ 9-4 Table 9-4: Increments of Reportable Values of Sky Cover Height ............................... 9-5 Table 9-5: Summary of Sky Condition Observing and Reporting Standards ................ 9-6 Table 10-1: Summary of Temperature and Dew Point Observing and Reporting Standards ................................................................................................ 10-2 Table 11-1: Units of Measure of Pressure Parameters .............................................. 11-2 Table 11-2: Summary of Pressure Observing and Reporting Standards.................... 11-3 Table 12-1: Reportable Visibility Values ..................................................................... 12-3 Table 12-2: Notations for Reporting Present Weather ............................................... 12-4 Table 12-3: Contractions for Sky Cover ..................................................................... 12-7 Table 12-4: Increments of Reportable Values of Sky Cover Height ........................... 12-7 Table 12-5: Type and Frequency of Lightning .......................................................... 12-11 Table 12-6: Units of Measure for Precipitation ......................................................... 12-14 Table 12-7: Characteristics of Barometer Tendency ................................................ 12-17 Table 12-8: 3-Hour Pressure Change ...................................................................... 12-18 Table C-1: Accuracy for Runway Visual Range .......................................................... C-1 Table C-2: Accuracy of Automated Visibility Sensors.................................................. C-1 Table C-3: Units of Measure, Range, Accuracy and Resolution of Wind Parameters ............................................................................................... C-2 Table C-4: Range and Accuracy of Sky Condition Parameters ................................... C-2 Table C-5: Temperature and Dew Point Sensor Accuracy and Resolution (Co) ......... C-2 Table C-6: Units of Measure, Range, Accuracy and Resolution of Pressure Parameters ................................................................................................ C-3 Table D-1: RVR Transmittance Conversion Table for Tasker 400 and Equivalent Systems with 250-Foot Baseline -- Contrast Threshold 5.5 Percent .......... D-1 Table D-2: RVR Transmittance Conversion Table for Tasker 500 and Equivalent Systems with 250-Foot Baseline -- Contrast Threshold 5.0 Percent. ......... D-2

Federal Meteorological Handbook No.1

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CHAPTER 1: INTRODUCTION

1.1 Purpose

Federal Meteorological Handbook No.1, Surface Weather Observations and Reports (FMH-1) defines the observing, reporting, and coding standards for surface based meteorological reports. These standards are applicable to all Federal agency programs.

These standards do not inhibit agencies from doing more than is specified.

1.2 Applicability of Standards

Standards described in this Handbook are applicable only if a station has the capability to comply. The phrase "at designated stations" refers to observing stations instructed by their responsible agency to perform a specified task. These specified tasks shall be performed in accordance with the standards described in this Handbook.

This Handbook is applicable to stations taking the following types of observations:

a) Automated - automated surface weather observing systems that prepare the meteorological reports for transmission without a certified weather observer.

b) Augmented - automated surface weather observing systems that prepare the meteorological reports for transmission with certified weather observers signed-on to the system to add information to the observation.

c) Manual - certified weather observers are responsible for the meteorological observations.

1.3 Relation to Other Handbooks and Manuals

Individual agencies shall issue their own manuals defining their observing procedures which implement the FMH-1 standards. Such manuals shall complement, not change, the standards contained in FMH-1. Most observing standards described in this Handbook also apply to synoptic surface observations which have coding and reporting procedures described in Federal Meteorological Handbook No.2, Surface Synoptic Codes (FMH-2). FMH-1 is consistent with agreements and publications of the World Meteorological Organization (WMO), the International Civil Aviation Organization (ICAO), specifically WMO No. 306 - Manual on Codes, and ICAO Annex 3 - Meteorological Services for International Air Navigation, and civil as well as military weather services.

1.4 Format of This Handbook

Chapter 1 presents an introductory overview of surface weather observations.

Chapter 2 discusses the surface weather observation program, types of observations, criteria for specials, general observing standards, and dissemination.

Chapter 3 presents the certification and quality control standards. It discusses certification of observers and quality control performed on-site, and at remote locations.

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Chapter 4 defines the requirements for maintaining records of surface weather data. It discusses the types of records, preparation and maintenance of the Station Information File, types of storage, and procedures for maintaining records of surface weather data.

Chapters 5 through 11 focus on a specific element (e.g., Visibility is an element) and all the associated parameters (e.g., Prevailing Visibility and Sector Visibility are visibility parameters) of that element that appear in the weather report. The elements are: Wind (Chapter 5), Visibility (Chapter 6), Runway Visual Range (Chapter 7), Present Weather (Chapter 8), Sky Condition (Chapter 9), Temperature and Dew Point (Chapter 10), and Pressure (Chapter 11). Each chapter contains a similar format: a brief overview of the chapter, a section that describes parameters, and a section that defines further the observing and reporting standards for the reports. Each chapter also contains a Summary Table that offers an abridged listing of standards described in the chapter. By design, these summary tables do not contain all of the details found in the text.

Therefore, these tables should only be used as an overview of the standards contained in the chapter.

Chapter 12 defines the coding procedures for reports in the METAR/SPECI format.

Appendix A is a Glossary.

Appendix B is a list of Abbreviations and Acronyms.

Appendix C lists Sensor Standards.

Appendix D contains Runway Visual Range Tables.

Throughout this Handbook, the following definitions apply:

a) "shall" indicates a standard is mandatory.

b) "should" indicates a standard is recommended.

c) "may" indicates a standard is optional.

d) "will" indicates futurity; it is not a requirement to be applied to standards.

1.5 Changes to The Handbook

Changes, additions, deletions, and corrections will be issued, as necessary. These changes shall be issued only by the Office of the Federal Coordinator for Meteorology (OFCM) after consultation and coordination with the Working Group for Federal Meteorological Handbook No. 1 (WG/FMH-1).

1.6 Agency Procedures and Procedural Changes

Agencies shall issue manuals and directives to provide more detailed instructions and training to their personnel and users (see paragraph 1.3). Copies of these procedures shall be provided to the reference library (see paragraph 1.7). Agencies may also issue changes to their procedures as follows:

a) Routine procedural changes that are in conformance with FMH-1 may be issued by an agency at any time without coordination with the WG/FMH-1.

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b) Procedural changes not in conformance with FMH-1 shall be coordinated with the WG/FMH-1when time allows. However, when necessary to meet urgent requirements, procedural changes not in conformance with FMH-1 may be issued by an agency without coordination with the WG/FMH-1. Copies of changes shall be forwarded to the WG/FMH-1for coordination and appropriate action.

1.7 Reference Library

The WG/FMH-1 shall maintain a record and library of agency procedures, changes, and supplements issued by all participating agencies. The WG/FMH-1shall establish a procedure for making these procedures, changes, and supplements available to users.

1.8 Unforeseen Requirements

No set of instructions can cover all possibilities in weather observing. Observers must use their own judgment, adhering as closely as possible to this Handbook and agency operating procedures, to describe phenomena not adequately covered by specific instructions. If the observer believes Handbook procedures require change or clarifica-tion, suggested changes should be sent through normal administrative channels to the headquarters of the appropriate organization.

1.9 Other Questions and Suggestions Regarding FMH-1

Questions or suggestions about the content or organization of this Handbook should be directed to:

Office of the Federal Coordinator for Meteorology 1325 East-West Highway, Suite 7130 Silver Spring, MD 20910 Telephone: Commercial (301) 628-0112

FAX (301) 713-1744

E-mail:ofcm.mail@noaa.gov mailto:ofcm.mail@noaa.gov

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CHAPTER 2: SURFACE WEATHER OBSERVATION

PROGRAM

2.1 General

Surface weather observations are fundamental to all meteorological services.

Observations are the basic information upon which forecasts and warnings are made in support of a wide range of weather sensitive activities within the public and private sectors.

2.2 Scope

This chapter briefly describes the Federal Government's surface weather observation program and outlines the observing program and procedures which apply to each of the agencies involved in surface weather observing. In addition, the chapter addresses the types of dissemination and the general requirements for verifying and making corrections to disseminated reports.

2.3 Surface Weather Observation Program

The Departments of Commerce (DOC), Defense (DOD), and Transportation (DOT) have established networks of stations that collectively provide the meteorological data used by the public and private sectors. As the Nation's primary civil meteorological agency, the DOC's National Weather Service (NWS) has the responsibility for observing, analyzing and forecasting weather conditions. DOD organizational elements within the U. S. Air Force (Major Commands), Marine Corps, and Navy (Naval Meteorology and Oceanography Command (NAVMETOCCOM)) take weather observations to support DOD operations worldwide. In addition to taking observations, the DOT's Federal Aviation Administration (FAA), as the agency responsible for safe operation of aircraft and efficient use of the Nation's airspace system, has the role of establishing requirements for, and disseminating aviation weather data to airspace users.

In addition to the observations taken by the above Federal agencies, observations are taken by commercial airline companies, private individuals, and local and state government agencies.

2.4 Aviation Weather Observing Locations

There shall not be more than one official observation for a specific location at any one time. For meteorological observations, the observing location is defined as the point or points at which the various elements of the observation are evaluated. At a large airport, the locations may be defined as follows:

a) For clouds, surface visibility, and weather, the observing location may be at the touchdown area of the primary runway.

b) For tower visibility, the observing location shall be the Airport Traffic Control Tower (ATCT).

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c) For temperature, dew point, and wind, the observing location may be the center of the runway complex.

d) For the location, type, and frequency of lightning (see paragraph 12.7.1.j(2)), the observing location may be the Airport Location Point (ALP) .

Specific details on the siting of observing equipment can be found in the Station Information File (see paragraph 4.3.1).Manual and augmented weather observations may also contain information on phenomena occurring at other than the station. In these cases, the point(s) where the phenomenon occurs is not considered to be an additional observing location.

2.5 Types of Reports

2.5.1 Aviation Routine Weather Report (METAR)

METAR is the primary observation code used in the United States to satisfy requirements for reporting surface meteorological data. METAR contains a report of wind, visibility, runway visual range, present weather, sky condition, temperature, dew point, and altimeter setting collectively referred to as "the body of the report". In addition, coded and/or plain language information which elaborates on data in the body of the report may be appended to the METAR. This significant information can be found in the section referred to as "Remarks". The contents of the remarks will vary according to the type of weather station. At designated stations, the METAR may be abridged to include one or more of the above elements.

2.5.2 Aviation Selected Special Weather Report (SPECI)

SPECI is an unscheduled report taken when any of the criteria given in paragraph 2.5.2.a have been observed. SPECI shall contain all data elements found in a METAR plus additional plain language information which elaborates on data in the body of the report. All SPECIs shall be made as soon as possible after the relevant criteria are observed.

a) Criteria for SPECI

1. WIND SHIFT. Wind direction changes by 45 degrees or more in less than 15 minutes and the wind speed is 10 knots or more throughout the wind shift.

2. VISIBILITY. Surface visibility as reported in the body of the report decreases to less than, or if below, increases to equal or exceed:

a) 3 miles.

b) 2 miles.

c) 1 mile.

d) The lowest standard instrument approach procedure minimum as published in the FAA’s Instrument Flight Procedures Information Gateway.

If none published, use 1/2 mile.

3. RUNWAY VISUAL RANGE (RVR). The highest value from the designated RVR runway decreases to less than, or if below, increases to equal or exceed https://www.faa.gov/air_traffic/flight_info/aeronav/procedures/

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2,400 feet during the preceding 10 minutes. U.S. military stations may not report a SPECI based on RVR.

4. TORNADO, FUNNEL CLOUD, OR WATERSPOUT.

a) is observed.

b) disappears from sight, or ends.

5. THUNDERSTORM.

a) begins (a SPECI is not required to report the beginning of a new thunder-storm if one is currently reported).

b) ends.

6. PRECIPITATION.

a) hail (including small hail) begins or ends.

b) freezing precipitation begins, ends, or changes intensity.

c) ice pellets begin, end, or change intensity.

d) snow begins, ends, or changes intensity.

7. SQUALLS. When squalls occur.

8. CEILING. The ceiling (rounded off to reportable values) forms or dissipates below, decreases to less than, or if below, increases to equal or exceed:

a) 3,000 feet.

b) 1,500 feet.

c) 1,000 feet.

d) 500 feet.

e) The lowest standard instrument approach procedure minimum as published in the FAA’s Instrument Flight Procedures Information Gateway.

If none published, use 200 feet.

9. SKY CONDITION. A layer of clouds or obscurations aloft is present below 1,000 feet and no layer aloft was reported below 1,000 feet in the preceding METAR or SPECI.

10. VOLCANIC ERUPTION. When an eruption is first noted.

11. AIRCRAFT MISHAP. Upon notification of an Aircraft Mishap unless there has been an intervening observation.

12. MISCELLANEOUS. Any other meteorological situation designated by the responsible agency, or which, in the opinion of the observer, is critical.

b) The SPECI criteria are only applicable to stations that have the capability of evaluating the event. For example, visually evaluated elements, such as a tornado, are not applicable to non-staffed automated stations.

2.6 Observing Standards Applicable to All Stations

2.6.1 Use of Certified Observers. All personnel performing an observation function shall be certified in accordance with paragraph 3.3.1. Certification may be limited in accordance with observer responsibilities.

https://www.faa.gov/air_traffic/flight_info/aeronav/procedures/

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2.6.2 Backup. Backup refers to a method, in accordance with agency procedures, for providing meteorological reports, parts of reports, documentation, or communication of reports when the primary method is unavailable.

2.6.3 Rounding Figures. Except where otherwise designated in this Handbook, the rounding of numbers shall be accomplished as follows: If the fractional part of a positive number to be dropped is equal to or greater than one-half, the preceding digit shall be increased by one. If the fractional part of a negative number to be dropped is greater than one-half, the preceding digit shall be decreased by one. In all other cases, the preceding digit shall remain unchanged. For example, 1.5 becomes 2, -1.5 becomes -1, 1.3 becomes 1, and -2.6 becomes -3.

2.6.4 Time Used in Reports. With the exception of designated stations which shall transmit reports in accordance with agency instructions, METAR shall be transmitted at fixed intervals with SPECI transmitted when any of the criteria in paragraph 2.5.2.a occurs or is noted. Each station's schedule for transmitting reports shall be included in the Station Information File (see paragraph 4.3.1).

a) Accuracy of Time in Reports. A procedure shall be established to assure that the accuracy of the timing device used to establish times in the observation program are within ±1 minute of the U.S. Naval Observatory time.

b) Scheduled Time of Report. The scheduled time of the METAR shall be the Coordinated Universal Time (UTC) a METAR is required to be available for transmission.

c) Actual Date and Time of Observation. The actual date and time of METAR shall be the time the last element of the observation was observed. The actual time of a SPECI shall be the time the criteria for the SPECI was met or noted.

d) Time Disseminated in Observations. All times disseminated in observations shall reference the 24-hour UTC clock, e.g., 1:47 A.M. shall be referred to as 0147 and 1:47 P.M. as 1347. The times 0000 and 2359 shall indicate the beginning and ending of the day, respectively.

e) Date and Time Entered in Observations. All dates and times entered in observations shall be with reference to the 24-hour clock. The times that are disseminated as part of the observation shall be entered in UTC. However, at the discretion of the responsible agency, those times used to otherwise document the observation or other related observational data may be either Local Standard Time (LST) or UTC. The time standard selected shall be clearly indicated on all records; if LST is used, the number of hours used to convert to UTC shall also be indicated.

2.6.5 Sensor Siting Standards. All installations of sensors shall be in accordance with the latest Federal Standard for Siting Meteorological Sensors at Airports published by the OFCM. Presently installed sensors may be operated at their present location. However, if they must be relocated, the Federal standards shall be followed.

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2.7 Recency of Observed Elements

2.7.1 Recency of Observed Elements at Automated Stations. Individual elements entered in an observation shall, as closely as possible, reflect conditions existing at the actual time of observation. For those elements that the human observer evaluates using spatial averaging techniques (e.g., sky cover and visibility), the automated station substitutes time averaging of sensor data. Therefore, in an automated observation, sky condition shall be an evaluation of sensor data gathered during the 30-minute period ending at the actual time of the observation. All other elements evaluated shall be based on sensor data that is within 10 minutes or less of the actual time of the observation.

2.7.2 Recency of Observed Elements at Manual Stations. Individual elements entered in an observation shall, as closely as possible, reflect conditions existing at the actual time of observation. Elements entered shall have been observed within 15 minutes of the actual time of the observation. Gusts and squalls shall be reported if observed within 10 minutes of the actual time of the observation. Observation of elements shall be made as close to the scheduled time of the observation as possible to meet filing deadlines, but in no case shall these observations be started more than 15 minutes before the scheduled time.

2.8 Dissemination

For purposes of this Handbook, dissemination is the act of delivering a completed report to users.

2.8.1 Types of Dissemination. There are two general types of dissemination:

a) Local. The transmission or delivery of a weather report to individual or groups of users in the service area of the weather station.

b) Long-line. The transmission of a weather report beyond the service area of the weather station.

2.8.2 Dissemination Requirements. All reports shall be given local dissemination. At designated stations, reports shall be given long-line dissemination. When reports are corrected, the corrected reports shall be given the same dissemination as the reports being corrected.

2.8.3 Dissemination Priority. If reports cannot be disseminated simultaneously, local and long-line, they should be disseminated first to the local airport traffic control users.

Further dissemination priorities shall be defined by the responsible agencies.

2.8.4 Corrections to Transmitted Data. Corrections shall be disseminated, as soon as possible, whenever an error is detected in a transmitted report. However, if the erroneous data has been superseded by a later report (with the same or more complete dissemination), it shall not be necessary to transmit the corrected report. Corrections transmitted shall consist of the entire corrected report. The original date and time of the report shall be used as the date and time in the corrected report.

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2.9 Report Filing Time

SPECIs shall be completed and transmitted, as soon as possible. Agencies shall establish filing deadlines for all METARs; the filing deadlines shall be no sooner than necessary to assure the availability of the report at its scheduled time. METARs shall not be transmitted sooner than 10 minutes before their scheduled time.

2.10 Delayed Reports

When transmission of an observation is delayed until time for the next regularly scheduled report, only the latest report shall be transmitted. In the record of observations, the remark FIBI (Filed but Impractical to Transmit) shall be appended in parentheses to the report that was not transmitted to indicate the report was not transmitted. The remark FIBI shall not be included in any local dissemination of the report.

When a SPECI is not transmitted long-line, the later SPECI shall be transmitted long-line only when the overall change between the last transmitted report and the current report satisfies the criteria for a SPECI. If the SPECI is not transmitted long-line, the remark FIBI shall be appended to the report in the record of observations. The SPECI shall be disseminated locally.

Reports of Volcanic Eruption shall be disseminated, by any means possible, regardless of the delay.

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CHAPTER 3: CERTIFICATION AND QUALITY

CONTROL

3.1 General

In order to ensure validity and reliability of the Federal Government's meteorological data, the use of standards, certification, and quality control must be an inherent program element. Without these essential elements, the credibility of the Nation's climatological database would become suspect and invoke mistrust.

3.2 Scope

This chapter prescribes the general standards for certification of observers and quality control of weather observations. It separately addresses the standards and procedures applicable to all stations. It also discusses the requirement for quality control at National Centers.

3.3 Certification Requirements

3.3.1 Certification of Observers. Agencies shall have an observer certification program, and only observers certified through that program shall be authorized to take weather reports.

The certification of the observer shall attest to the fact that in the view of the certifying agency the observer has:

a) Acceptable vision. The observer shall have distant vision of at least 20/30 (Snellen) in at least one eye, corrected if necessary.

b) Adequate Training. The level of training would be commensurate with the level of the weather reporting function to be undertaken by the candidate.

c) Demonstrated Ability to Take Required Weather Reports. This demonstrated ability would be dependent on the level of the weather reporting function to be undertaken by the candidate.

3.3.2 Certification of Stations. All stations where weather reports are taken shall be approved by the responsible agency. The procedures for the approval shall also be established by that agency and include consideration of:

a) the instruments to be used meeting the minimum standards for accuracy, range, and resolution for weather elements as prescribed in this document (Appendix C);

b) the installation of the automated sensors satisfying the siting requirements prescribed in the Federal Standard for Siting Meteorological Sensors at Airports;

3.4 Quality Control

3.4.1 Quality Control of Observing Programs. Each agency shall establish a quality control program to ensure that their surface weather reporting stations utilize proper procedures. The primary objective of the quality control program shall be to ascertain that:

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a) the siting and exposure of instruments is the best practical, and are still within acceptable limits;

b) instruments are in good order and have been compared to the standard sensors, as required;

c) standard procedures are being used to generate weather reports at the station;

d) the observation program at the station satisfies the requirements for weather reports at that location; and

e) any observers taking weather reports are certified.

3.4.2 Quality Control of Instruments and Sensors

a) Comparison of Portable Transfer-Standard Sensors. Agencies shall establish a procedure to routinely compare portable transfer-standard instruments and sensors, which are used during station inspections, to standards that ensure compliance with the accuracy requirements, as listed in Appendix C, of this Handbook.

b) Comparison of Instruments and Sensors. Agencies shall establish a procedure to periodically compare the instruments and sensors used at operational weather reporting stations to standards that ensure compliance with the accuracy requirements, as listed in Appendix C, of this Handbook.

c) Calibration and Standardization of Sensors. Agencies shall establish procedures to calibrate and standardize sensors. Calibration and standardization should be performed at least annually, after installation, and after any major maintenance is performed on a sensor.

d) Routine Maintenance. Each agency shall establish a schedule of maintenance for equipment at stations. Unless relieved of the responsibility, observers at stations shall determine the operational acceptability of meteorological equipment consistent with agency policy. In addition to having the responsibility for the operational status of meteorological equipment, the observer shall also have the final authority for deciding the operational status of any meteorological equipment used in the weather reporting program.

3.4.3 Quality Control of Weather Reports. Each agency shall establish a near real-time quality control program for all stations. This program shall be used to quickly detect repetitious errors being made by observers at the station. The program may use station personnel or personnel at another location with access to the records and reports made at the station.

a) Pre-Dissemination Quality Control. The quality control performed at surface weather reporting stations prior to any dissemination of the weather report is the most important of all quality control operations. Once an erroneous report has been given to users, it is impossible to ensure that corrections are received by that same group of users. Therefore, all operational weather reporting stations shall have as high a level of pre-dissemination quality control procedures as practicable. This check should consist of recalculating computed data, verifying the syntax of the recorded weather reports, and comparing the recorded weather report against the reports recorded on any local dissemination devices.

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b) Post-Dissemination Quality Control. All surface weather reports shall be checked at the site for errors after dissemination and prior to the next weather report. If possible, the disseminated report shall be compared with the original report to verify that no errors were generated during the dissemination process.

3.5 Quality Control Performed at Central Locations

Insofar as possible, all agencies should implement quality control checking at a central location on a timely basis. Agencies shall devise a method to provide feedback to the observer in the case of errors detected in manual weather reports.

3.6 Customer Feedback

Agencies shall encourage customers to comment on the performance of their observing programs. In this context, customers are anyone utilizing the data from the programs.

It is recommended that all public issuances of information on the observing systems include an address of the office designated to process customer feedback.

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CHAPTER 4: OBSERVATIONAL RECORDS

4.1 General

All meteorological data collected as part of the surface weather observation program are valuable information. Consequently, these data require retention, storage, and archival.

4.2 Scope

This chapter prescribes the minimum standards for maintaining a record of the operational status of weather reporting stations and maintaining records of surface weather reports. Because of the lasting value of all the data collected in the surface weather reporting program, agencies are encouraged to devise methods to store as much of the data as possible within their physical and financial constraints. Because of the generally common interest in historical and archived data, agencies shall provide records to the National Centers for Environmental Information (NCEI).

4.3 Types of Records

4.3.1 Station Information File. Each agency shall establish a Station Information File for each station under their jurisdiction. The file shall be a record of characteristics of each station. The lists below presents a list of data required from most stations. Copies of all Station Information Files shall be available upon request from the responsible agency when needed to interpret weather records from a particular station.

Physical Characteristics

• Station Name

• Airport Name

• Station Identifier

• WMO Index Number

• Time Zone

• Latitude/Longitude

• Climatological Elevation

• Field Elevation

• Ground Elevation

• Station Elevation

• Type of Station

• Description of Significant Topography

Observation Schedule

• Types of Reports

• Schedule for Reports

• Hours of Operation

Observation Program

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• Elements Observed

• Long-Line Communications Circuits

• SPECI

• Transmitted (Y/N)

Sensor Data

• System Configuration

• Types of Sensors

• Location of Sensors

• Non-standard sensor siting

a. Maintenance of Station Information File. The Station Information File should be created on or before the date of station establishment to ensure the timely notification of the station's existence. The file shall be updated when any data listed in 4.3.1 or in the file changes, or the station closes, noting the date when each change is implemented. Corrections to erroneous station information shall be noted as such, along with the historical extent of the error. Agencies shall establish procedures to ensure the validity of their stations' Station Information Files. It is recommended that the content of the most recent file be reviewed as part of each station inspection.

b. Station Information File at NCEI. A copy of the Station Information File for each observing location shall be sent to the agency group representatives (NOAA, U.S.

Navy, and U.S. Air Force) at the Federal Climate Complex, Asheville, North Carolina, and made available to the DOC/NOAA/NCEI. A copy of the file shall be sent when a station is established, when any data listed in 4.3.1 or in the file changes or is corrected, and when a station closes. This file shall become a part of that station's archived record.

4.3.2 Retention of Station Observational Records. Station observational records include regularly observed meteorological data from manual stations and automated systems. Each agency shall define procedures for retaining all observational records in accordance with agency data retention and archival schedules under general METAR/SPECI guidelines:

a) Short-term Storage. Storage of observational records for 4 or more days is required to assist in sensor/system maintenance, and verification of sensor/system records in the event of an aircraft mishap.

b) Long-term Retention. Each agency shall establish procedures to provide long-term retention of all observational records for 5 years to satisfy requirements for local studies and to support litigation.

c) Archive. The DOC/NOAA/NCEI is responsible for archiving observational records, as necessary, to satisfy requirements to monitor the Nation's climate.

Agencies shall include procedures to ensure the delivery of observational records to the agency group representatives (NOAA, U.S. Navy, and U.S. Air Force) at the Federal Climate Complex.

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4.3.3 Station System/Sensor/Configuration Records. Each agency shall maintain information about changes in the configuration of each station's systems/sensors, and in their operational status. This information may be collected as part of the Station Information File or the Station Observational Records and, as such, maintained, retained, and archived as outlined in the preceding Sections.

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5-1

CHAPTER 5: WIND

5.1 General

Wind shall be measured in terms of velocity, a vector that includes direction and speed.

5.2 Scope

This chapter prescribes the standards for observing and reporting wind data.

5.3 Wind Parameters

As used in this chapter, wind is the horizontal motion of the air past a given point and includes:

a) Direction. The direction, in tens of degrees, from which the wind is blowing.

b) Speed. The rate, in knots, at which the wind passes a given point.

c) Gusts and Squalls. Descriptions of the variability of the wind speed.

d) Peak wind speed. The maximum instantaneous wind speed measured.

e) Wind Shift. A change in wind direction.

5.4 Wind Observing Standards

Wind direction, speed, and gusts shall be determined at all stations. All other wind related parameters shall be determined at designated stations.

5.4.1 Wind Direction.

The wind direction shall be determined by averaging the direction over a 2-minute period. When the wind direction sensor(s) is out of service, at designated stations, the direction may be estimated by observing the wind cone or tee, movement of twigs, leaves, smoke, etc., or by facing into the wind in an unsheltered area.

5.4.2 Variable Wind Direction.

The wind direction may be considered variable if, during the 2-minute evaluation period, the wind speed is 6 knots or less. Also, the wind direction shall be considered variable if, during the 2-minute evaluation period, it varies by 60 degrees or more when the average wind speed is greater than 6 knots.

5.4.3 Wind Speed.

The wind speed shall be determined by averaging the speed over a 2-minute period. At designated stations, Table 5-1 shall be used to estimate wind speeds when instruments are out of service or the wind speed is below the starting speed of the anemometer in use.

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5.4.4 Wind Gust and Squall.

The wind speed data for the most recent 10 minutes shall be examined to evaluate the occurrence of gusts or squalls. Gusts are indicated by rapid fluctuations in wind speed with a variation of 10 knots or more between peaks and lulls. Squalls are indicated by a sudden onset of wind where the speed increases by at least 16 knots and is sustained at 22 knots or more for at least a minute. The speed of a gust or a squall shall be the maximum instantaneous wind speed.

5.4.5 Peak Wind Speed.

Peak wind data shall be determined with wind speed recorders. The peak wind speed shall be the maximum instantaneous speed measured since the last routine METAR.

Table 5-1. Estimating Wind Speed

Knots Specification Knots Specification

<1 Calm; smoke rises vertically. 22-27 Large branches in motion; whistling heard in overhead wires; umbrellas used with difficulty.

1-3 Direction of wind shown by smoke drift not by wind vanes. 28-33 Whole trees in motion; inconvenience felt walking against wind.

4-6 Wind felt on face; leaves rustle; vanes moved by wind. 34-40 Breaks twigs off trees; impedes progress.

7-10 Leaves and small twigs in constant motion; wind extends light flag. 41-47 Slight structural damage occurs.

11-16 Raises dust, loose paper; small branches moved. 48-55 Trees uprooted; considerable damage occurs.

17-21 Small trees in leaf begin to sway;

crested wavelets form on inland waters. 56-71 Widespread damage.

5.4.6 Wind Shifts.

Wind data shall be examined to determine the occurrence of a wind shift. A wind shift is indicated by a change in wind direction of 45 degrees or more in less than 15 minutes with sustained winds of 10 knots or more throughout the wind shift.

5.4.7 Wind Sensor Range, Accuracy, and Resolution.

The required range, accuracy, and resolution for wind sensors are listed in Appendix C.

5.5 Wind Reporting Standards

5.5.1 Units of Measure and Resolution for Wind.

Wind direction and speed shall be reported in the body of all observations. Direction shall be reported in tens of degrees with reference to true north and speed shall be reported in knots (see paragraph 12.6.5).

5.5.2 Calm Winds.

When no motion of air is detected, the wind shall be reported as calm (see paragraph 12.6.5.d).

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5.5.3 Variable Wind Direction.

When the wind direction is variable, a variable wind entry shall be reported as part of the wind group in the body of the report (see paragraphs 12.6.5.b and 12.6.5.c).

5.5.4 Wind Gust.

When a gust is detected within 10 minutes of the actual time of the observation, the maximum instantaneous speed shall be reported (see paragraph 12.6.5.a). The squall shall be reported as present weather (see paragraph 8.5.3.c and 12.6.8.e(1)).

5.5.5 Peak Wind Data.

The peak wind shall be reported in the remarks section whenever the maximum instantaneous speed in knots (since the last METAR) is greater than 25 knots (see paragraph 12.7.1.d).

5.5.6 Wind Shifts.

The wind shift and the time of occurrence shall be reported in the remarks section (see paragraph 12.7.1.e).

5.6 Summary of Wind Observing and Reporting Standards

Table 5-2 summarizes the wind observing and reporting standards.

Table 5-2. Summary of Wind Observing and Reporting Standards

Parameter Observing and Reporting Standard

Wind direction 2-minute average in 10 degree increments with respect to true north is reported.

Wind speed 2-minute average speed in knots is reported.

Wind gust The maximum instantaneous speed in knots in the past 10 minutes is reported.

Wind squall The maximum instantaneous speed in knots is reported

Peak wind The maximum instantaneous speed in knots (since the last scheduled report) shall be reported whenever the speed is greater than 25 knots.

Wind shifts Wind shift and the time the shift occurred are reported.

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6-1

CHAPTER 6: VISIBILITY

6.1 General

Visibility is a measure of the opacity of the atmosphere. An automated, instrumentally-derived visibility value is a sensor value converted to an appropriate visibility value and is considered to be representative of the visibility in the vicinity of the airport runway complex. A manually-derived visibility value is obtained using the "prevailing visibility" concept. In this chapter, the term "prevailing visibility" shall refer to both manual and instrument derived visibility values.

6.2 Scope

This chapter describes the standards for observing and reporting visibility.

6.3 Visibility Parameters

The visibility parameters are:

a) Prevailing visibility. The visibility that is considered representative of visibility conditions at the station; the greatest distance that can be seen throughout at least half the horizon circle, not necessarily continuous.

b) Sector visibility. The visibility in a specified direction that represents at least a 45 degree arc of the horizon circle.

c) Surface visibility. The prevailing visibility determined from the usual point of observation.

d) Tower visibility. The prevailing visibility determined from the airport traffic control tower (ATCT) at stations that also report surface visibility.

6.4 Visibility Observing Standards.

Visibility may be manually determined at the surface, the tower level, or both. If visibility observations are made from just one level, e.g., the airport traffic control tower, that level shall be considered the "usual point of observation" and that visibility shall be reported as surface visibility. If visibility observations are made from both levels, the visibility at the tower level may be reported as tower visibility.

Visibility may be automatically determined by sensors and a visibility algorithm that calculates a mean visibility, which is the sensor equivalent of prevailing visibility. The visibility data during the period of observation are examined to determine if variable visibility shall be reported.

6.4.1 Observing Sites.

Where the observer's view of the horizon is obstructed, the observer shall move to as many locations as necessary and practicable within the time allotted for the observation to view as much of the horizon as possible. In this respect, natural obstructions, such as trees, hills, etc., are not obstructions to the horizon. These natural obstructions define the horizon.

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For automated weather observing stations, the visibility sensor shall be located, in accordance with the Federal Standard for Siting Meteorological Sensors at Airports.

6.4.2 Manual Observing Aids.

Agencies shall establish procedures to ensure that insofar as possible, dark or nearly dark objects viewed against the horizon sky shall be used during the day, and unfocused lights of moderate intensity (about 25 candela) shall be used during the night as reference points for manually determining visibility. In addition, visibility sensors may be used to assist the observer in the evaluation.

6.4.3 Observer Adaptation to Ambient Light Conditions.

Agencies shall establish procedures to ensure that observer's eyes shall be accustomed to the ambient lighting conditions before manual visibility observations are taken.

6.4.4 Visibility.

Manually-derived visibility shall be evaluated as frequently as practicable. All available visibility reference points shall be used. The greatest distances that can be seen in all directions around the horizon circle shall be determined. When the visibility is greater than the distance to the farthest reference point, the greatest distance seen in each direction shall be estimated. This estimate shall be based on the appearance of the most distant visible reference points. If they are visible with sharp outlines and little blurring of color, the visibility is much greater than the distance to them. If they can barely be seen and identified, the visibility is about the same as the distance to them.

After visibilities have been determined around the entire horizon circle, they shall be resolved into a single value for reporting purposes. To do this, the greatest distance that can be seen throughout at least half the horizon circle, not necessarily continuous shall be used; this is prevailing visibility. If the visibility is varying rapidly during the time of the observation, the average of all observed values around the horizon circle shall be used for reporting purposes.

6.4.5 Variable Prevailing Visibility.

If the prevailing visibility rapidly increases and decreases by 1/2 statute mile or more, during the time of the observation, and the prevailing visibility is less than 3 miles, the visibility is considered to be variable.

6.4.6 Sector Visibility.

When the manually-derived visibility is not uniform in all directions, the horizon circle shall be divided into arcs that have uniform visibility and represent at least one eighth of the horizon circle (45 degrees).